<?php
session_start();
$result = array();
for($i=0;$i<5;$i++){    
    if($_SESSION['del'] == $i * 100) continue;
    array_push($result, [
        'firstname' => 'rock',
        'lastname' => 'jin',
        'phone' => $i * 100,
        'email' => 'aaa@bnvd.com'
    ]);
}

echo json_encode($result);
?>